The aim of this study was to determine the effects of Bacillus licheniformis CQN-12, B. amyloliquefaciens CQN-2, and B. subtilis CQN-39 originally isolated from the gut of a healthy sea cucumber (Apostichopus japonicus), on the growth performance, gut microbiota and immune response of sea cucumbers (A. japonicus). Sea cucumbers were fed a commercial pellet feed supplemented with B. licheniformis CQN-12, B. amyloliquefaciens CQN-2 or B. subtilis CQN-39 at different concentrations (0 (control), 10⁷ and 10⁹ CFU/g respectively), for 60 days. Our results revealed that that dietary B. licheniformis CQN-12 and B. amyloliquefaciens CQN-2 (10⁷ CFU/g optimal concentration) enhanced growth performance, up-regulated innate immunity and altered microbial colonization in the gut of sea cucumbers whereas dietary B. subtilis CQN-39 had no significant effect. Furthermore, diets supplemented with an optimal concentration of B. licheniformis CQN-12 and B. amyloliquefaciens CQN-2 stimulated the mRNA expression of superoxide dismutase, lysozyme, and catalase. In conclusion, our study suggests that B. licheniformis CQN-12 and B. amyloliquefaciens CQN-2 could be used in feed supplements for healthier production of sea cucumbers in artificial farms.

中文翻译：

---

芽孢杆菌的作用。海参（Apostichopus japonicus）的生长、肠道菌群组成和免疫力

本研究的目的是确定最初从健康海参 ( Apostichopus japonicus )肠道中分离的地衣芽孢杆菌CQN-12、解淀粉芽孢杆菌CQN- 2 和枯草芽孢杆菌CQN-39对生长性能的影响、海参（A. japonicus）的肠道微生物群和免疫反应。用商业颗粒饲料喂养海参，补充有不同浓度的地衣芽孢杆菌CQN-12、解淀粉芽孢杆菌CQN-2 或枯草芽孢杆菌CQN-39（分别为 0（对照）、10 ⁷和 10 ⁹ CFU/g）， 60 天。我们的研究结果表明，饮食B. licheniformis CQN-12 和B. amyloliquefaciens CQN-2（10 ⁷ CFU/g 最佳浓度）增强了海参的生长性能，上调了先天免疫并改变了海参肠道中的微生物定植，而膳食枯草芽孢杆菌CQN-39 具有无显着影响。此外，添加最佳浓度的地衣芽孢杆菌CQN-12 和解淀粉芽孢杆菌CQN-2 的饮食刺激了超氧化物歧化酶、溶菌酶和过氧化氢酶的 mRNA 表达。总之，我们的研究表明B. licheniformis CQN-12 和B. amyloliquefaciens CQN-2 可用于饲料添加剂，以在人工养殖场中更健康地生产海参。